Sensor unit, radiation detector and method of manufacturing a sensor unit

Abstract

A sensor unit (14) for a radiation detector (12), the sensor unit (14) comprising a conversion element (22) comprising a plurality of imaging pixels (30), wherein each imaging pixel (30) is configured to directly convert radiation into an electrical charge and wherein each imaging pixel (30) comprises a charge collection electrode (28); and a readout substrate (24) comprising a plurality of readout pixels (32), wherein each readout pixel (32) is connected to an associated imaging pixel (30) by means of an interconnection (36) at a connection position on the charge collection electrode (28); wherein each readout pixel (32) has a smaller area than an associated imaging pixel (30) of the plurality of imaging pixels (30); and wherein the connection positions in relation to the charge collection electrodes (28) are varied with respect to a neighboring charge collection electrode (28). A radiation detector (12) and a method of manufacturing a sensor unit (14) are also provided.

The invention claimed is: 
     
       1. A sensor unit for a radiation detector, the sensor unit comprising:
 a conversion element comprising a plurality of imaging pixels,
 wherein each imaging pixel is configured to directly convert radiation into an electrical charge, and 
 wherein each imaging pixel comprises a charge collection electrode; and 
 
 a readout substrate comprising a plurality of readout pixels,
 wherein each readout pixel is connected to an associated imaging pixel by means of an interconnection at a connection position on the charge collection electrode; 
 wherein each readout pixel has a smaller area than an associated imaging pixel of the plurality of imaging pixels; 
 wherein the connection positions in relation to the charge collection electrodes are varied with respect to a neighboring charge collection electrode; and 
 wherein the plurality of readout pixels are arranged in at least two readout groups such that at least one street is formed between the readout groups and a separation between adjacent pixels across a corresponding one of the at least one street is greater than a separation between adjacent pixels within a single readout group of the at least two readout groups. 
 
 
     
     
       2. The sensor unit according to  claim 1 ,
 wherein the readout pixels in each readout group are more compactly arranged than the associated imaging pixels, or wherein each readout group has a smaller area than an associated imaging group, wherein each imaging pixel in each imaging group is connected to an associated readout pixel in a corresponding readout group. 
 
     
     
       3. The sensor unit according to  claim 2 , further comprising vias arranged in the at least one street. 
     
     
       4. The sensor unit according to  claim 2 , further comprising common electronics for at least two readout pixels at least partly arranged in the at least one street. 
     
     
       5. The sensor unit according to  claim 1 ,
 wherein each readout pixel has a readout pixel first width in a first direction and each imaging pixel has an imaging pixel first width in the first direction, and 
 wherein the readout pixel first width is smaller than the imaging pixel first width. 
 
     
     
       6. The sensor unit according to  claim 5 ,
 wherein the readout pixels in each readout group are more compactly arranged in the first direction than the associated imaging pixels such that one of the at least one street is formed in the first direction between the readout groups, or 
 wherein each readout group has a first width in the first direction that is smaller than a first width in the first direction of each imaging group such that one of the at least one street is formed in the first direction between the readout groups, and 
 wherein each imaging pixel in each imaging group is connected to the associated readout pixel in the corresponding readout group. 
 
     
     
       7. The sensor unit according to  claim 1 ,
 wherein each readout pixel has a readout pixel first width in a first direction and a readout pixel second width in a second direction, 
 wherein each imaging pixel has an imaging pixel first width in the first direction and an imaging pixel second width in the second direction, 
 wherein the readout pixel first width is smaller than the imaging pixel first width, 
 and wherein the readout pixel second width is smaller than the imaging pixel second width. 
 
     
     
       8. The sensor unit according to  claim 7 ,
 wherein the readout pixels in each readout group are more compactly arranged in the first direction and in the second direction than the associated imaging pixels such that the at least one street is formed in the first direction and in the second direction between the readout groups, or wherein each readout group has a first width in the first direction and a second width in the second direction that is smaller than a first width in the first direction and a second width in the second direction of each imaging group such that the at least one street is formed in the first direction and in the second direction between the readout groups, and 
 wherein each imaging pixel in each imaging group is connected to the associated readout pixel in the corresponding readout group. 
 
     
     
       9. The sensor unit according to  claim 1 , wherein each interconnection comprises a solder bump. 
     
     
       10. A radiation detector comprising at least one sensor unit according to  claim 1 . 
     
     
       11. A radiation detector comprising at least two sensor units according to  claim 1 , wherein an edge imaging pixel of each sensor unit is within one imaging pixel width of an edge imaging pixel of an adjoining sensor unit. 
     
     
       12. The sensor unit according to  claim 1 , wherein each readout pixel comprises readout pixel electronics with at least one electronic component specific for an associated readout pixel. 
     
     
       13. The sensor unit according to  claim 12 , wherein the at least one electronic component comprises at least one of an amplifier, a comparator or a counter for counting photon pulses. 
     
     
       14. A method of manufacturing a sensor unit with a conversion element connected to a readout substrate, the method comprising:
 providing the conversion element comprising a plurality of imaging pixels,
 wherein each imaging pixel is configured to directly convert radiation into an electrical charge and wherein each imaging pixel comprises a charge collection electrode, wherein a plurality of outer edge imaging pixels of the conversion element define boundaries of a conversion element effective area; 
 
 providing the readout substrate comprising a plurality of readout pixels,
 wherein a plurality of outer edge readout pixels of the readout substrate define boundaries of a readout substrate effective area, 
 
 wherein each readout pixel has a smaller area than an associated imaging pixel of the plurality of imaging pixels, and
 wherein the plurality of readout pixels are arranged in at least two readout groups such that at least one street is formed between the readout groups and a separation between adjacent pixels across a corresponding one of the at least one street is greater than a separation between adjacent pixels within a single readout group of the at least two readout groups, and 
 
 connecting each charge collection electrode of the imaging pixels on a surface of the conversion element to a readout electrode of an associated readout pixel on a first surface of the readout substrate by means of an interconnection at a connection position on the charge collection electrode, 
 wherein the conversion element effective area has a substantially same area as the readout substrate effective area. 
 
     
     
       15. The method according to  claim 14 , wherein the readout substrate includes readout pixel electronics with at least one electronic component specific for each readout pixel and common electronics for at least two readout pixels formed in the at least one street between readout groups of the readout pixels. 
     
     
       16. The method according to  claim 15 , further comprising:
 etching at least one via through the at least one street of the readout substrate,
 wherein the at least one street is void of the readout pixel electronics for specific readout pixels. 
 
 
     
     
       17. The method according to  claim 14 , further comprising:
 providing a support substrate comprising a plurality of support contact pads and a plurality of transmission lines coupled to the support contact pads; and 
 connecting the support contact pads on a surface of the support substrate to one or more of the readout pixels or to common electronics through at least one via on a second surface of the readout substrate, opposite the first surface, by means of an interconnection. 
 
     
     
       18. The method according to  claim 14 , wherein connecting the charge collection electrode to the readout substrate or connecting the support substrate to the readout substrate uses at least one of solder bump bonding, direct bonding, or flip-chip bonding. 
     
     
       19. The method according to  claim 14 , wherein the conversion element effective area is at least 1% larger than the readout substrate effective area. 
     
     
       20. A sensor unit manufactured by the method according to  claim 14 .